x=number of books that cost 0.60
y=number of books that cost 0.75
x+y=16
0.6x+0.75y=10.95
solve
multiply second equation by 10 for nicity
6x+7.5y=109.5
multiply first equesiotn by -6 and add to second
-6x-6y=-96
6x+7.5y=109.5 +
0x+1.5y=13.5
1.5y=13.5
divide both sides by 1.5
y=9
sub back
x+y=16
x+9=16
minus 6
x=7
seven 0.60 books and nine 0.75 books
